1. Chapter 3.7 Pages 64 – 70

2. Learning outcomes State the energy changes that occur when solids melt and liquids vaporise Explain the values of enthalpy of melting (fusion) and vaporisation are. Explain the physical properties of ionic solids, metals, macromolecular solids, and molecular solids in terms of their detailed structures and bonding List the three types of strong bonds List the three types of intermolecular forces Describe how melting temperatures and structure are related Describe how electrical conductivity is related to bonding Specification ref: 3.1.3

3. The three states of matter In groups – write down on paper what you can recall about the particle model (things to think about… arrangement of particles, spacing of particles, movement) Why does the temperature of a solid not change when it is melting?

4. Energy changes on heating Find and define the terms: Enthalpy Enthalpy change of melting Enthalpy change of vaporisation

5. Types of crystal The physical properties of a material depend on its structure. Materials in which the atoms or molecules have a regular arrangement (lattice) are called crystals. There are four basic types of crystal: molecular (simple covalent) – a regular lattice of covalently-bonded molecules held together by intermolecular forces. macromolecular (giant covalent) – a regular lattice of atoms held together by covalent bonds. metallic – a regular lattice of positively-charged metal ions surrounded by a ‘sea’ of delocalized electrons. ionic – a lattice formed by positively and negatively-charged ions.

6. Properties of ionic substances

7. Properties of sodium chloride

8. Properties of metallic substances

9. Properties of metallic and ionic crystals

11. The structure of diamond Allotropes are different forms of the same element. Each carbon atom is bonded by covalent bonds to four other carbon atoms, creating a rigid, very strong 3D structure. Diamond is an allotrope of carbon, and is an example of a macromolecular crystal.

12. Properties of diamond

13. The structure of graphite Graphite is another allotrope of carbon. Like diamond, it is a macromolecular crystal. However, it has very different physical properties because the carbon atoms are arranged in a different way. Each carbon atom is covalently bonded to three others in the same 2D plane, forming layers. These layers are held weakly together by van der Waals forces, not covalent bonds.

14. Properties of graphite

15. Allotropes of carbon

16. Other allotropes of carbon Buckminsterfullerene is one type of fullerene. It contains 60 carbon atoms, each of which is bonded to three others by two single bonds and one double bond. Carbon nanotubes are another type of fullerene. They are cylindrical carbon molecules. They have many potential applications, such as transporting drugs around the body and as components in electrical transistors. Another class of carbon compounds are the fullerenes.

17. The structure of iodine Solid iodine has a molecular structure consisting of a regular arrangement of iodine molecules (I 2 ) held in place by van der Waals forces. The melting point of iodine is low (387 K) compared to that of diamond, because less energy is required to break van der Waals forces than covalent bonds.

18. The structure of ice In ice, water molecules form four hydrogen bonds with neighbouring water molecules, creating a repeating tetrahedral structure. Usually a solid is more dense than the same material in its liquid phase. However, cold water (around 4 °C) is denser than ice. This is because not all the water molecules are hydrogen bonded, and the mean distance between molecules is less than the hydrogen bond length. hydrogen bond

19. Covalent crystals: true or false?

20. Covalent structures

21. Homework Learn the definitions for a test the first week back Complete the practice questions in the text book (pg 71) Complete the pack of questions shared on Show My Homework